In the beverage industry, for example, in breweries, the cleaning of bottles, their filling and labelling, etc. are mainly carried out automatically. Thus, for example, semiautomatic plants are capable of conveying approximately 2000 bottles and more per hour; fully automatic plants can handle up to approximately 80,000 bottles and more per hour.
During the filling operation, the bottles are conveyed on belts, the so-called "apron conveyors", most of which are made of stainless steel. These chain-type belts are lubricated with a chain sliding or lubricating agent, also known as "belt lubricant". Also, these conveyor belts must be cleaned, usually at more or less regular intervals.
In breweries, potash-based soft soaps, to which, for example, wynthetic monionic or ionic surfactants may be added, are preferably used as lubricatiing agents. A disvantage of these lubricating agents is that the potash-based soaps are sensitive to water hardness. Therefore, sequestering agents such as ethylenediamine tetraacetic acid, which partly mask the hardness, are also added as a rule.
If the water is hard, the familiar problems associated with hard water occur, i.e., the effectiveness of the lubricating agent is reduced, and also, for example, the precipitated calcium salts can lead to lubrication problems, because they do not, as do the alkali metal soaps, reduce the friction resistance between bottle and chain. There is also the danger that the carbonic acid in the water and the CO.sub.2 from the air will cause the fatty acids to precipitate, which can also lead to lubrication problems.
Another disadvantage when using potash-based soft soaps as lubricating agents is that, although precipitated lime soaps and fatty acids are readily bio-degradable, they also represent a good nutrient substrate for bacteria. Thus, there develops under the chains and between the chain links a slime which very rapidly leads to the production of unpleasant odors due to bacterial degradation. The slime thus formed must therefore be jetted away frequently with water, for example by means of a high-pressure gun. Nevertheless, it is not possible to stop the production of odors completely; moreover, the slime which has been flushed away naturally also develops the foul smell elsewhere.
It is also known in the art to use, instead of potash-based soft soaps, synthetic lubricating agents, particularly those with an amine base, which do not have the disadvantages of potash-based fat soaps. However, these cationic lubricating agents are sensitive to anions, with the result, in particular, that the nozzles through which the lubricating agents are metered onto the conveyor belts become clogged over time. Thus, such lubricating agents react in particular with anions, such as carbonates and sulfates, which are present in abundance in the water used. The same reactions may also occur on the belts, so that the poorly soluble products formed by the reaction of the belt lubricant with anions reduce the lubricating or sliding effect.
Therefore, the need still exists in the beverage industry, especially in breweries, to improve the belt lubrication and the cleaning of the conveyor belts.